https://www.reuters.com/article/us-health-coronavirus-google/big-tech-starts-requiring-vaccines-twitter-closes-re-opened-u-s-offices-idUSKBN2EY2NK

(Reuters) -Twitter Inc is shutting its reopened offices in United States, while other big tech companies are making vaccination mandatory for on-campus employees, as the highly infectious Delta COVID-19 variant drives a resurgence in cases.